The service "has not taken part in such actions since 1959," when a Soviet KGB agent in Munich assassinated Stepan Bandera, a Ukrainian nationalist, a spokesman for the service, Boris Labusov, was quoted as saying.

Wanted

Mr Yanderbiyev was acting Chechen president in 1996.

He headed the rebel delegation which held talks with Russian President Boris Yeltsin and Prime Minister Viktor Chernomyrdin in the same year.

He has been included on the Interpol wanted list since 2001.

The leader of Chechnya's pro-Moscow administration President Akhmad Kadyrov told Russia's Interfax news agency: "Yanderbiyev was the chief ideologue of the separatists and later of their terrorist organisations.

"You will find no one in Chechnya who will regret what happened to Yanderbiyev."

The former Chechen leader had been living in Qatar for three years and Moscow repeatedly sought his extradition.

He was viewed as a key figure behind the 1999 Chechen incursion into Dagestan.

He was also suspected of links to the siege of a Moscow theatre in October 2002 that left 130 hostages dead.

Mr Yanderbiyev was considered a key link in the Chechen rebels' fundraising network from abroad.